Effect of hot-water extraction (HWE) severity on bleached pulp based biorefinery performance of eucalyptus during the HWE–Kraft–ECF bleaching process

• About 50% xylan-based sugar was recovered by hot-water extraction (HWE) with a P-factor of 738.
• Intensified HWE resulted in significant xylan-based sugar degradation and lignin condensation.
• Good handsheet was produced from HWE (P-factor = 198)–Kraft–ECF bleaching process.
• Moderate HWE induced bleached pulp meets the requirements of dissolving pulp.
• Bleached pulp-based biorefinery performance could be balanced by severity of HWE.

The effectiveness of a biorefinery based on an HWE–Kraft–ECF bleaching process and the end use of pulp was systematically evaluated. Using a P-factor of 198, nearly 30% of xylan-based sugars were recovered. The resulting pulp and paper properties were found to be comparable with the control. A maximum xylan-based sugar recovery of nearly 50% was achieved at a P-factor of 738. Although the strength of this P-factor induced handsheet was lower than that of the control by about 20%, the corresponding pulp was sufficient for dissolving pulp application. However, once the P-factor rose above 1189, hemicellulose sugars were significantly degraded into furans; pulp and paper properties were also deteriorated due to cellulose degradation, lignin deposition and condensation. Thus, considering the different end use of pulps, the performance of an HWE-based biorefinery could be balanced by its HWE severity.

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